Microservices vs Monoliths: When to Choose Each

When you build an application, you choose an architecture. Two popular options are a monolith and a set of microservices. A monolith is a single codebase and a single deployment. Microservices split the work into small, independent services that communicate over a network.

Monoliths are simple to start with. With one codebase, teams can move fast, test end-to-end, and deploy with a single process. If the domain is small and traffic is predictable, a monolith often avoids complex coordination.

But as the product grows, changes in one area can affect others. Scaling is harder because you scale the whole app, not just part. Teams may collide, and new tech needs can require a big rewrite.

Microservices offer independence: teams own services, deployment schedules are decoupled, and you can scale hot spots. They fit large, evolving products and diverse tech stacks. They also improve fault isolation, so a failure in one service doesn’t crash the whole system.

Yet they bring complexity: network calls, data consistency, and deployment coordination. You need strong governance, observability, and good API contracts. Start with clear boundaries and automation.

Start with a modular monolith, where modules have clear boundaries and a shared build. Use the strangler pattern to replace parts with services over time. Define bounded contexts and align teams to those domains. Keep data ownership clear.

For a mid-size online shop, you might keep catalog and user management in the same monolith but move checkout or payments to separate services later. This lets you scale demand without rewriting everything.

Choosing between monolith and microservices is not a one-time decision. It is a path. Start simple, measure, and evolve as needs grow.

Key Takeaways

• Pick a monolith for simplicity and speed
• Move to microservices for scale and autonomy
• Start with a modular monolith and a gradual decomposition